One small point.  All the functions you list there do indeed go together except for one, the router.  A router actually comes into physical contact with the material being formed.  This is a totally different beast than a torch table on many levels.  It needs to be several times more rigid for one thing.  So relatively heavy.  These are attributes you try to avoid in a torch table.

A CNC router should be a totally different machine from the start.  MUCH heavier frame, servo motors instead of steppers, proper linear ways, ball screw drives, much longer Z axis and a very flat table.

The Dawg

You are correct, there are some machines designed to use steppers.  But steppers will only get you so far.  Where as servos are considered a proper industrial component. 

Here is another example of a good but slow milling machine using steppers as you have stated:

http://www.tormach.com/

And here is a much more heavy duty machine (still a hobby machine) using servos:

http://www.ihcnc.com/


One issue with steppers is they tend to have no encoders with them.  The reasoning I guess is a stepper is a cheap digital motor already, why add another digital element to it.  Without this encoder there is no positional feedback.  We call this an open loop system.  You tell the stepper to go here and you assume it went.  There is no way to know if it did or not.  If your design is well matched to the loads present, then you'll probably never lose position.

On the other hand, servos are basically a brushed DC motor with a digital encoder coupled to it's shaft.  The drivers for these motors include a closed loop system that constantly monitors the motors position.  It can't lose its position.  If it gets overloaded it trips an alarm and stops so you know there's an issue.  There are other reasons why I think a servo is better, this having to do with torque curves.

They are more expensive however, so if you can make do with a stepper for light duty or slow work then do it.  For the torch table, as long as we have no need to go fast, steppers are the way to go.  Well, a torch can only cut so fast anyway, so perfect.


K2 machines are very light duty.  They are only useful for routing wood and plastics.  Yes, I know they say they can machine non ferrous metals but trust me, they really can't do it effectively.  Then we get into trying to machine steel, then forget it.

When I say effectively I mean it should be able to proceed without over stressing itself to the point of damage.  Also, it should be able to machine the material in a timely fashion.  No point having a machine that has to take tiny tiny nibbles and take all afternoon to machine a part when a proper setup can do it in 15 minutes flat.  This is not an exaggeration either.  Then on top of that, if after a few months you realize that the machine is self destructing, you realize that the manufacturer was not really being totally honest.

Lets just make sure we are comparing apples with apples....:)

Also, I hate to be poo poo'ing but very few multi machines I've seen work anywhere as good as their single function counterparts.  As long as we realize that a multi function machine is a compromise then great.

The Dawg

@ FactorChris - Well, I feel your pain my friend.  CNC programming is one of my professions.  It is not something we're ever going to be able to "print".  There are way too many variables involved.  I'm compiling your next packet of goodies and I'll include some of this topic.

If I was there with you I would have that thing screaming in a few days.  But I also have many thousands of dollars worth of software to aid me and years of experience as a guide.  I have some serious reservations about this Gcode converter.  I'm not sure it's the way to go.

If you guys have a vector you need converted to Gcode, send it to me.  I will ask a bunch of questions and then send you something to chew on.

But go through the links I'm going to send you now because I have a message I sent to Marcin a while back that deals with this very topic.

The Dawg

@ Jason - Actually I was referring to links to messages on this forum.  But if there is any reference material you need on this topic I could try and send it your way.  I have access to a lot of downloads.

As far a conversions, it's not like an export filter in Photoshop.  I take the vector into a CAM environment and set all sorts of parameters to explain how I want the machine to move in relation to this path.  So the vector is really just the very beginning.  Also, after I've got a tool path generated in this environment there is yet another layer called post processing.  This takes into account any special machine dependent codes that change from one controller to another.

I just went through my old projects and took some screen captures to illustrate what I'm talking about.  Hopefully you find this interesting.

I have a series of images below that go from a set of vectors (lines) to a finished cut simulation.

First file is the vectors.
Second is the 3D model
Third is a complex roughing tool path (the red lines)
Forth is a simulation of the path as it would look in the milling machine.
Fifth is the final tool path.
Sixth is the final simulation.

Now this is quite a bit more complex than a torch table tool path.  But many of the same considerations come into play.

The Dawg

Water cutting could also be added to the XYZ table.  It makes some sense for materials like large sheets of plastic.

- Mark